1. Field of the Invention
The present invention relates to a wavelength distribution measuring apparatus for homogenizing light dispersed from a predetermined region of an object to be measured, to thereby detect wavelength distribution characteristics.
2. Description of the Related Art
A colorimeter is one of the measuring apparatuses for measuring the spectrum of light beams radiated from an object to be measured. A colorimeter is an apparatus for numerically measuring color information, and used for inspecting the color quality of industrial products and goods in various fields such as automobile, foods, printing, and the like, and for performing color correction in a microscope.
There is known a colorimeter which has an optical system for uniformizing light beams radiated from a predetermined region on an object to be measured and irradiating the light beams onto an optical sensor including a color filter transmitting different wavelength components and a plurality of light receiving elements such as CCD and CMOS. There are various optical systems for a colorimeter which uses a plurality of light receiving elements to perform measurement.
As an optical system for homogenizing light beams, there are known an optical system including an optical fiber (see, for example, JP H06-273232 A) and an optical system including a light beam homogenizing optical element such as a light pipe (see, for example, JP 2008-096777 A). Light beams are reflected a plurality of times by the inside surface of the light beam homogenizing optical element, to thereby homogenize illuminance distribution of the light beams, so that an optical sensor can be irradiated with homogenous light beams.
On the other hand, when a microscope is used to measure a spectrum of light beams, a specimen may be enlarged via an objective lens to form an intermediate image, and the intermediate image thus formed may be defined as a field of measurement. In this case, the enlarged image of the specimen serves as a field of measurement, and therefore, the divergent light beams from the specimen have a smaller numerical aperture (NA) in the field of measurement, and often approximate to parallel light beams. When such light beams are made incident on the light beam homogenizing optical element, there arises a problem that the light beam homogenizing optical element needs to be increased in length in order to homogenize the light beams through reflections by the inside surface of the light beam homogenizing optical element.
In view of the above, a diffuser plate is disposed between the field of measurement and the light beam homogenizing optical element. The diffuser plate allows substantially parallel light beams to be converted into divergent light beams, to thereby reduce the total length of the light beam homogenizing optical element, which makes it possible to attain size reduction of the apparatus.